The objective of this research program is the development of a three dimensional technique for the accurate description of spinal deformity. This three dimensional x-ray technique will be used to further the understanding of the pathomechanics of spinal deformity through the application of engineering technology. The descriptive technique is based on bi-plane radiography with the resulting films being digitally encoded and analyzed by a computer. The results of the analysis can be displayed by the computer in either orthographic projections on a plotter or stereoscopic views which may be manipulated by the clinician on a large scale cathode ray tube. The conditions of spinal deformity which will be investigated include spinal fusion and scoliosis.